This invention relates generally to controlling the print density in printers.
Mono-laser printers may contain device parameters, commonly called operating points, that control the density or darkness of the print on a page. The density control parameters may be defined for each engine speed and also for special media types.
The operating points may be stored in tables in print engine firmware. The table values in the engine firmware are determined during the printer development cycle. A cartridge and printer pair determined to have nominal components is used to determine the values to be stored in the engine firmware tables.
A density control operating point table may have sixty rows that determine the laser power, duty cycle, and developer bias voltage. The density control operating point selected by the printer depends on the print engine speed, print resolution, user-selected darkness, media type, and other factors.
Changing the print engine's density control table is impractical after the start of printer production because of the large number of printers in customer' hands that would need to receive the revised firmware. Thus, print engine density control tables are modified through the use of adders that are stored in cartridge memory devices. The adders, stored in the cartridge memory devices, modify the index of the current density operating point table that is currently selected.
The resolution of available adjustment with an adder is limited. A four-bit value may used to encode an adder that has only 16 possible values. The adder is typically applied to more than one operating point table with the possibility of unintended effects.
Thus, there is a need for better ways to enable modification of density control tables.